Making Etherchannel

[shahid_raza74]

Hi,

I want to make Etherchannel (b/w two 2950 switches by using both Gigabit uplink ports of each switch)...

can anybody help me?

Regards,

Shahid Raza

[ankurbhasin]

Hi Sahid,

Have a look at the same config it is just a imaginary port numbers and channel group number you can use as per your requirement

Switch# configure terminal

Switch(config)# interface range gig0/23 - 24

Switch(config-if)# channel-group 5 mode desirable

Switch(config-if)# end

Apply the same config on the other 2950 also and you are good to go

Also have a look at this for config guide with examples for cofiguring etherchannel on 2950 switch

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12120ea2/2950scg/swethchl.htm#wp1033981

HTH, if yes please rate the post.

Ankur

[shahid_raza74]

Thanks Ankur,

But before implementing these commands I want to know that which Protocol (PAgP OR LACP) will run after this command and if this will run LACP or PAgP then why LACP or why PAgP...I mean I want to know both protocols Advantages/Disadvantages, which is easy to implement and which is good etc.

Can you compare EtherChannel with RSTP? theat which is more efficient method and give lowest Link Failover time etc???

I will be very thankful to you.

Regards,

Shahid Raza

[ankurbhasin]

Hi Shahid,

PAGP is a cisco propritary protocol and lacp is open standard protocol.

If you are implementing an etherchannel between 2 cisco switches I will recommend you to use PAGP protocol and incase you are implementing an etherchannel between cisco switch and some other switch you are left with no option other than LACP.

You cannot compare Etherchannel and RSTP both are different technology. Etherchannel is used to bundle more than one physical port for more throughput, loadbalancing and redundancy is there is one port goes down WHEREAS RSTP is a advance version of STP for faster conversion.

I hope this gives you a brief idea about your question.

HTH, if yes please rate the post.

Ankur

[devang_etcom]

no you can not compere the etherchannel and rstp...both are the different technology...etehrechannel is used to create the bundle between multiple port where as RSTP is the loop avoidance technology in switch network but it is much more faster then the STP...

rate this post if it helps

regards

Devang

[shahid_raza74]

Thanks Ankur and Devang, but actually I want to know that both EtherChannel and RSTP gives link fault Tolerant, although the method of both EtherChannel (give link fault tolerant using etherchannel Load Balnacing method) and RSTP (through its own calculation based method), so which will give faster reconvergence like RSTP gives normally 2 seconds but what abt. EtherChannel. Actually I just want to implement any one (either RSTP or EtherChannel) b/w Two 2950 switches just to get fault tolerant so that if one link fails then other will active asap.

Now, lastly, I have some more questions reg EtherChannel, as follows, pls. clear it:

Q1:I read, both Protocols of EtherChannel (PAgP and LACP) adds the EtherChannel Group to the Spanning-tree as a single Switch, so do we need to configure Spanning-tree before configuring EtherChannel so that it can use STP as stated above?

Q2: As we can configure EtherChannel bu using PAgP, LACP or Manually, so what is meant by Manually, how we can do this?

Q3:Pls. clear EtherChannel Load Balncing Two methods (i.e. Souce-MAC address and Destinatination-MAC addres Methods)...I have to implement b/w Two core 2950 switches and b/w On core and One Access Switches, which Load Balncing method I should use in both cases?

Q4: Lastly, can you tell me which of the Two EtherChannel Protocols (PAgP and LACP) gives lowest convergence time in case of one link of EtherChannel fails...any standard time in Milliseconds or Seconds?

I will be very much thankful.

Regards,

Shahid

[ankurbhasin]

Hi Shahid,

1) As I told RSTP is advance version of STP and is used for loop avoidance so you cannot compare with etherchannel. If you have 2 parallel ports connected between 2 2950 one will be blocked by STP but if you want both to be in forwarding state and give you more throughout you have to configure the 2 ports in one etherchannel and then both will be in fwding state so that is the reason it is said that etherchannel group is been added to the STP as a single switch or else if it is not a etherchannel one port will be blocked by STP.

2) PAGP or LACP is used for automatic creation of EtherChannels by exchanging packets between Ethernet interfaces but if you do not want any protocol to be running what you can do is manually configure etherchannel with mode as "ON" and this will stop use of PAGP and LACP and that is what is mentioned as Manually but you have to make sure that both the sides the etherchannel mode is "ON"

3) The etherchannel load balancing can be done source base or destination base ,ac address methids and which one to use depends on your network design and requirmeent of etherchanel. I will suggest you to understand first the 2 methods and then deploy one which most suits your network. To undersdtand the load balancing method just read this simple link

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12113ea1/2950scg/swethchl.htm#1020011

4) When any of the link in etherchanel fails the port does not get converged but the traffic gets converged because one of the port is already up and running fine so traffic will take few milliseconds to move through the other working port. In etherchanel as you know some traffic pass by one port and some by another and if one link fails all traffic will conferge and start going from single link which will not take much time.

As you in STP ports is block and if fwding port goes down the port is converged but in etherchannel both the ports are fwding and if one port goes down traffic converges.

So do not compare etherchannel with STO or RSTP at all.

Also read this link about etherchannel for more undetstanding

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12113ea1/2950scg/swethchl.htm#wp1096986

HTH, if yes please rate the post.

Ankur

[shahid_raza74]

Thanks Ankur,

Lastly, as you written EtherChannel Configuration commands in your v. first reply,i.e.

Switch# configure terminal

Switch(config)# interface range gig0/23 - 24

Switch(config-if)# channel-group 5 mode desirable

Switch(config-if)# end

I want to ask you two things only which will resolve my query...

Q1- In the above commands "channel-group 5", what/why is 5?

Q2- Lastly, just for example, to configure RSTP, I use the command"spanning-tree mode rapid-pvst", but to customize configuration of RSTP I will go to adjust/configure RSTP Parameters like, Max.age, Hello Time etc....Similarly, in EtherChannel configuration what are its Parameters so I can configure/adjust these parameters...Kindly mention EtherChannel Parameters, Its Function and its configuration commands?

I will be very thankful and sure that your reply will resolve my query.

Regards,

Shahid Raza

[devang_etcom]

shahid,

here channel-group 5 means you are making this perticular interface member of the channel-group number 5... and this number is only having local significant...so it not big issue...

in ether-channel you can also have the load sharing...which is also very good feature...

look at this link: http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

hope this will help

regards

Devang

[shahid_raza74]

Thanks but I am waiting for my second question's answer to resolve my query:

Q2- Lastly, just for example, to configure RSTP, I use the command"spanning-tree mode rapid-pvst", but to customize configuration of RSTP I will go to adjust/configure RSTP Parameters like, Max.age, Hello Time etc....Similarly, in EtherChannel configuration what are its Parameters so I can configure/adjust these parameters...Kindly mention EtherChannel Parameters, Its Function and its configuration commands?

I will be very thankful and sure that your reply will resolve my query.

Shahid

[ankurbhasin]

Hi Shahid,

As I told you in my previous posts you cannot compare etherchannel with RSTP. Both are different technologies and are used for different purposes.

Only thing you can configure in etherchannel is the way it perform loadbalancing. You can also configure PAgP Learn Method and Priority and LACP port priorities and Configuring Hot Standby Ports.

Have a look at this link

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12113ea1/2950scg/swethchl.htm#1057322

You cannot do anything more in etherchannel.

Regards,

Ankur

[devang_etcom]

hi shahid,

BPDU sent at every 2 second and Max age timer of it is 20 seconds, then you can have edge port which is very similar to the port fast.

other thing is RSTP can only achieve rapid transition to forwarding on edge ports and on point-to-point links. The linktype is automatically derived from the duplex mode of a port. A port operating in full-duplex will be assumed to be point-to-point, while a half-duplex port will be considered as a shared port by default.This automatic link type setting can be overridden by explicit configuration.

so by varing above all parameters you can adjust...

and more information you can have on this link:http://www.cisco.com/application/pdf/en/us/guest/tech/tk621/c1501/ccmigration_09186a0080174993.pdf

and about ether channel you just need to take care of the both the end configuration mode ...and still wait for other replies...

but that document on RSTP will help you...

rate this post if it helps

regards

Devang